Distillation of lignite



June 6, 1933. H. DEBAUCHE 1,912,974

DISTILLATION OF LIGNITE Filed March 31, 1950 baadm Patented June 6,1933

PATENT OFFICE HUBERT DEBAUCH'E, OF GOUILLET, BELIIGIUM DISTILLATION' ormomma Application filed March 31, 1930, Serial no. 440,467, and in GreatBritain December 17, 1929.

This invention relates to the treatment of lignite for the purpose oftransforming it into a coke which is suitable for the manufacture ofbriquettes, ovoids and the like.

The invention contemplates subjecting the said li nite to lowtemperature distillation and subsequently to a high temperaturedistillation in order to produce a coke which will be of the characterdesired, and involves the use of a furnace or oven for this purpose, ofa kind known as the Rolle furnace which may be constructed as describedand shown in my prior Patent No. 1,713,032. This patent specificationdescribes an improved form of Rolle furnace, but to carry the inventioninto effect it is not essential that such improved form of furnaceshould be used, although it is preferable to do so.

It is well known that good coal briquettes or ovoids made in closedmoulds with a coal composed of fragments of a size from O m. m. to 1 m.m., having a proportion of 7 70 of pitch and a pressure of 225 kilos persquare centimeter possess the following qualities:

1. They present great cohesion.

2. Water exercises no action on these briquettes or ovoids. Consequentlyif they are immersed for a long time in water, for example for 300 to400 consecutive hours, they absorb very little water (about 10% of theirweight) and not only do they not disintegrate under the action ofthewater, but their cohesion does not decrease.

If these briquettes are taken from the water, they return to theiroriginal weight by the evaporation of the water absorbed.

These briquettes can resist indefinitely and without any alteration allatmospheric influences. i

3. In a locomotive fire box or other furnace, these briquettes burnwithout disintegrating. e These briquettes and ovoids which aresatisfactory for commercial requirements, will 15 be referred tohereinafter as good coal briquettes.

On the contrary, when lignite semi-coke is taken as produced by variousexisting distilling furnaces and ground to the dimensions of a size from0 m. m. to 1 m. m. and

:converted into briquettes in closed moulds,

with 7 76 of pitch and a pressure of 225 kllOS per square centimeter orit may be ovoids, the following is observed: 1 1. The cohesion of thesebriquettes is very 2. The Water exercises a powerful chemical action onthese briquettes- Immersed in the water during only 150 to 200 hours,these briquettes absorb as much 0 as 25% of water and completelydisinte- If these briquettes are withdrawn from the water, they do notreturn to their original weight owing to the chemical action of the o5absorbed Water. Consequently, these briquettes cannot resist atmosphericinfluences indefinitely without alteration.

3. In a locomotive fire box or other type of furnace these briquettesdisintegrate under the action of fire.

Such briquettes and ovoids which do not satisfy-commercial requirements,will be referred to in the present specification as: inferiorbriquettes.

It is reasonable to conclude from the preceding that these inferiorlignite semicoke briquettes are incapable of use in almost any case. 7

By very prolonged researches and experiments, the inventor hasdiscovered:

- 1. That the three defects which are indicated above and which arealways present in r the inferior briquettes of lignite semi-coke are dueto the fact that the semi-coke used made in closed moulds with 7 ofpitch and a pressure of 225 kilos per square centimeter and they willpossess the three ualities of good coal briquettes mentioned a ove, thatis to say that:

1. The briquettes made with such lignite semi-coke will possess greatcohesion.

2. Water will exercise no action on these briquettes. Consequently ifone immerses them in the water for a long-time, for example during 300or 400 consecutive hours, they absorb very little water (about 10% oftheir weight) and not only will they not disintegrate in the water buttheir cohesion will not be decreased. When these briquettes arewithdrawn from the water, they will return promptly to their originalweight by the evaporation of the water absorbed. These briquettes willresist atmospheric influences indefinitely without any alteration.

3. In a locomotive fire-box or other furnace, these briquettes will burnwithout disintegration and even without cracking.

These briquettes and ovoids of lignite semicoke which satisfy thecommercial requirements hereinafter will be referred to as: good lignitesemi-coke briquettes.

The good lignite semi-coke with which these good briquettes and ovoidsmay be made will be referred to in the present specification as: speciallignite semi-coke.

This special lignite semi-coke presents characteristics which arepeculiar to it and which are found only in the lignite semi-coke whichis produced under certain well determined conditions, but which are notmet with in other lignite semi-cokes.

The researches and experiments made by the inventor have enabled him todiscover that, in order to obtain good briquettes of lignite semi-cokeof which the three chief qualities have been herewith enumerated, it isessential that the lignite semi-coke used for their manufacture, shouldpossess the two characteristic properties as follows:

A. The fragments of semi-coke must be clean and brilliant, that is tosay, they must not" become coated during the distillation with a thincoat of graphitic amorphous carbon, because this coating results inneutralizing to a very serious extent the binding action of the pitchand consequently renders the cohesion of the briquettes veryunsatisfactory.

B. Each fragment of semi-coke must be completely deprived of all theheavy hydro carbons contained therein.

Indeed, the presence of heavy hydrocarbons in a lignite semi-cokedenotes that the semi-coke contains particles of lignite of which thechemical transformation which takes place by the distillation isincomplete and if briquettes are made with such semicoke, the followingis observed:

1. Immersed in the water, the briquettes absorb water up to about 25% oftheir weight and sometimesmore.

2. The water absorbed'by these briquettes exercises a chemical actionwhich disintegrates them completely.

3. In a locomotive fire-box or other furnaces these briquettes willdisintegrate under the fire action.

The reason that a lignite semi-coke, although containing only a smallamount of heavy hydrocarbons gave after agglomeration only a badbriquette, was hitherto unknown, and the discovery that this was due tothe presence of heavy hydrocarbons is the result of numerous researchesand experiments made by the inventor.

These two characteristic properties A and B do not exist in the lignitesemi-coke which was hitherto made and which is produced by the' variousdistilling furnaces; this is the reason Why this lignite semi-cokecannot give and does not give after agglomeration good briquettes butonly bad briquettes.

On the contrary the special lignite semicoke made in accordance with theinvention possesses in thehighest degree the two characteristicproperties A and B and consequently it gives good briquettes whichpossess the three chief qualities mentioned above.

The process by which this special lignite semi-coke is produced andwhich is an object of the present invention, must employ both lowtemperature distillation and a high temperature distillation. Thelignite to be distilled must be gradually heated in such a way as toextract the utmost quantity of oil at the lowest temperature possible.Then the temperature of distillation must be progressive 1y increased soas to reach the high temperature, owing to the difficulties which are encountered in the elimination of the last particles of oil.

With the lignite which was employed in the experiments carried out bythe inventor, the low temperature distillation commenced at 300 C. andwas almost entirely completed at about 450 C.500 0., but for the removalof the last traces of heavy hydrocarbons it was necessary to raise thetemperature to about 800 C., for the semi-coke inside the retort, andwhich would correspond to a temperature of 1000 C. to 1100 C. for thehot gases in the flues at the lowest portion of the furnace.

It will be understood that the temperatures employed will vary accordingto the lignite treated, and that the above temperatures are sible withthe gas and vapours produced by the distillation itself so as to preventthe semicoke fragments being covered by a thin coating of graphiticamorphous carbon.

Further, the researches and experiments made by the inventor, haveresulted in the discovery that good briquettes of lignite semi-coke,that is to say briquettes manufactured with lignite semi-coke possessingthe two characteristic properties A and B mentioned above, possess asupplementary quality which exists only in a very much less degree inthe coal or good briquettes of coal. This supplementary quality, is theready combustibility which is far greater for good briquettes of lignitesemi-coke, than for the coal or the good briquettes of coal.

In the course of the researches and experiments made on an industrial s-ale by the inventor in Belgium and in New Zealand on locomotives whiledrawing normal trains or on steam boilers, it was undeniably verifiedthat in the same locomotive lire box or other furnace, a very muchhigher weight of good briquettes of lignite semi-coke could be burnedthan is the case with coal or good briquettes of coal. This differenceamounted to from to This higher combustion of good briquettes of ligniteseI11i-cokc-, naturally means a greater production of steam for the sameboiler and it can be concluded therefore, that the use of goodbriquettes of lignite semi-coke in steam locomotives or in marineboilers constitutes a considerable reserve of power which is aconsideration when it is a question of hauling a train on a prolongedincline or accelerating the speed of a train or steamer.

There is no doubt that this remarkable property of good briquettes oflignite scmicoke constitutes a strong argument in favour of theiremployment.

The enormous combustibility of good briquettes of lignite semi-coke wasnot hitherto known and this discovery is the result of the numerousresearches and experiments on a large scale made by the inventor on goodbriquettes of lignite semi-coke, that is to say, on the briquettesmanufactured with lignite semi-coke possessing the characteristic properties A and B mentioned above.

The applicant has also discovered that a Rolle furnace is particularlysuitable for this treatment of lignite in as much as it produces justthe conditions necessary to ob tain the special lignite semi-coke withthe characteristic properties mentioned.

The Rolle furnace, the use of which is known for low temperaturedistillation, has been invented for' the distillation of the lignites inSaxony which contain much oil and more than 50% of water. Such a furnacehas hitherto been employed exclusively for distilling oil and benzolfrom carbonaceous material and the coke hitherto produced was regardedat the best as a more or less unimportant by-product.

The inventor, however, discovered that the Rolle furnace offers greatadvantages for the treatment of lignite so as to obtain as its mainproduct the coke desired and the oil or benzol obtained by distillationbecomes therefore a by-product.

It thus follows that an object of the present invention is to utilize aRollo furnace for the distillation of lignito to produce the particularkind of coke necessary for being subscquently briquetted. v

'In carrying the invention into effect, the accompanying drawingillustrates a vertical section of a Rollo furnace suitable to thepurpose of the present invention.

According to the drawing the furnace comprises a central verticalcylindrical retort a into which the fuel is fed at its upper end Z) andfrom the lower end 0 of which the coke is periodically withdrawn. Theretort chamher is formed by a centre tubular chamber formed by a seriesof superimposed rings d of conical form and spaced apart a suitabledistance so as to permit the distillate escaping into the centre spaceand being led away by the usual outlet pipes 6.

Such a form of furnace is preferably modified by regulating thethickness of the annu lar layer f of fuel whereby as the lignite sinksprogressively downwards, the thickness of such annular layer becomesthinner as at 9 towards its lower end, Owing to the heat treatment whichis thus applied to the lignite, the latter is never in contact, duringthe distilling operation, with the hot gases which cause distillationand thus the fragments of semi-coke obtained are not covered by a coatof graphitic amorphous carbon, and nearly all the quantity of oilcontained in the lignite is extracted at low temperature. After this oilhas been removed, there remains in the semi-coke only a small quantityof heavy hydrocarbons and it is essential that these must be extracted,as has been mentioned above, in the form of oil in bringing thedistillation to a higher temperature which is a high temperaturedistillation so that no heavy hydrocarbons are retained and consequentlyno particles of insufficiently distilled lignite are left in the cokewhich will assist or tend to cause disintegration of the briquetteformed from the coke when exposed to moisture or to fire.

The coke produced in such a furnace is found to be clean in characterand shows a brilliant appearance and will be easily agglomerated aftercrushing with the normal proportion of pitch or other binder with theresult that very great cohesion of the briquettes is obtained and asuitable proportion of pitch would be 7.5% of'the mass. Further, thebriquette will not crack when ex posed to heat, it will possess veryhigh calorific value and itwill not disintegrate in the presence ofmoisture or fire.

From the foregoing it will be understood that by the use of thedescribed form of furnace or oven and the temperature treatmentindicated lignite is treated in such a way that a coke or semi-coke isproduced which is very suitable for the use of briquettes or ovoids andon test these have been shown to possess just those characteristicswhich are necessary to ensure economic commercial manufacture and use.

As tested for driving locomotives, the briquettes have been found to beeconomical as being able to drive or haul a load with a greater speedthan could be done by means of ordinary coal or briquettes as preparedin other ways.

Having now described my invention, what I claim as new and desire tosecure by Letters Patent is The process of producing a semi-coke for themanufacture of briquettes by continuously feeding downwardly through aheating zone of two different temperature ranges, a confined thinannular column of lignite, subjecting this annular column of lignitefirst to a temperature of 300 C. to 500 C., the heating being appliedindirectly and to the outer periphery of the column of lignite, and thensubjecting this heat treated column of lignite as it is fed furtherdownwardly to a temperature of 800 (1., the heating being appliedindirectly and to the outer periphery of the column to convert thelignite to a semicoke, withdrawing the distillation vapors and gasesevolved from the lignite in its passage through the heating zonesinwardly to a central zone at numerous points throughout the height ofthe column of lignite and selectively conducting off these evolvedvapors at different levels from this central zone.

In testimony whereof I have signed my name to this specification.

HUBERT DEBAUCHE.

